The present invention relates to improvements in apparatus for supplying flowable substances from one or more sources to one or more consumers. More particularly, the invention relates to improvements in apparatus which can be utilized with advantage to replenish or to maintain at least substantially constant the supplies of a flowable substance in the tanks, pots and/or other suitable receptacles in pasters and/or other types of machines wherein the supply of a continuously or intermittently consumed flowable material must be replenished, either continuously or at regular or irregular intervals, e.g., depending upon the requirements of one or more consumers.
Typical examples of consumers of flowable materials are so-called pasters which are utilized in machines for packing cigarettes or other rod-shaped smokers' products, e.g., to apply a suitable adhesive (such as hotmelt) to selected portions of discrete or coherent blanks which are to be converted into packets (e.g., the so-called hinged lid packets or soft packets), cartons or other types of enclosures. The blanks can be made of or can contain metallic foil, plastic foil, cardboard, pasteboard, paper or the like.
It is known to replenish the supply of an adhesive in the tank or pot of a paster by resorting to a suction nozzle having an intake end which draws adhesive from successive vessels and delivers a stream of adhesive to the tank or pot (hereinafter called tank) of the paster. Such apparatus operate satisfactorily as long as the intake end of the nozzle dips into a dwindling supply of adhesive in a vessel. However, problems can (and often to) arise when the supply of adhesive in a first vessel is exhausted or is depleted below a minimum acceptable level, i.e., when the intake end of the nozzle must be withdrawn from such (empty or nearly empty) vessel to be introduced into the supply of adhesive in another vessel. Thus, if the delivery of adhesive to a consumer (such as a paster in a cigarette packing machine) is interrupted for a certain interval of time, the machine begins to turn out defective products (such as cigarette packets or cartons of cigarette packets) or is automaticallly brough to a halt. This can entail huge losses in output, especially if the adhesive consuming machine forms part of a full production line, e.g., a production line employing one or more cigarette makers, one or more filter rod makers, one or more filter tipping machines, one or more makers of cigarette packets, one or more carton filling machines, and so forth.
For example, if the supply of adhesive in a vessel is exhausted while the pump which is connected with the suction nozzle continues to draw fluid by way of the suction intake of the nozzle, the latter supplies a column of air in lieu of a continuous stream or flow of adhesive. Such situation can arise while the production line is in actual use, e.g., as a result of exhaustion of the supply of adhesive in a battery or another group of vessels which serve to supply adhesive to the suction intake of the nozzle serving to supply adhesive to the tank or tanks of one or more pasters. A consequence of unsatisfactory operation of the adhesive supplying or replenishing system is that the entire production line must be brought to a halt in order to remove the rejects, to evacuate air from the passage or passages defined in part by one or more suction nozzles, and to reestablish a supply of adhesive-containing vessels.